1. Field of the Invention
The invention relates to a transport disc for an opening device of a printed sheet feeder, wherein such a transport disc is arranged on one or both opening drums of the opening device and has at its circumference an outer elastic support. An individual printed sheet can be clamped for its transport to a transport device between the elastic support and the disc of another opening drum.
2. Description of the Related Art
Feeders are provided to open the printed sheet removed from a stack and to place it onto a transport device, especially a collecting chain. For opening the printed sheet, such feeders have two opening drums B and C which grip the printed sheet to be opened respectively at the free sheet ends and open it. After opening of the sheet, the grippers or suction devices release the ends of the sheet. After release from the grippers or suction devices, it is important that the printed sheets are transported farther by transport discs until they fall onto the collecting chain in an astride position.
Feeders, and especially gather-stitcher feeders, must generally be able to process printed products of different thickness and also of various paper types. The transport discs accordingly must be able to safely transport respective products of different thickness. The transport discs thus not only must be able to receive different products of different thickness, but also to clamp very thin and unstable products with sufficient clamping force so that the sheets are transported and placed geometrically precisely onto the collecting chain.
In the prior art transport discs are known which have an elastic support made of a silicone hose about their circumference. The silicone hose is radially compressed according to the thickness of the products. Such a silicone hose presents problems in that it is difficult to fasten such a silicone hose on the body of the transport discs. Moreover, the clamping force which is exerted by the silicone hose is difficult to control. Alternatively, supports made of strip-shaped cellular rubber are known. The strips are glued onto the body of the transport disc. Depending on the cellular rubber density, the pressing forces can vary greatly. Moreover, this support is very susceptible to wear and tear and is not flexible. This support therefore must be exchanged frequently in a comparatively rather complicated manner.